What to do if spruce ever gets rare & pricey...

[Bob Hammond]

Look at this:

http://deredactie.be/permalink/1.2362321

I have some nice offcuts from soundboards for experimentation.

[Alan Carruth]

But then what do you do when petrochemicals become rare and pricey?

Actually, you can use ANY softwood instead of spruce, so long as you compensate for the difference is density. Young's modulus along the grain tracks the density pretty well, and in the same way for all softwoods, so things like pine can make a good soundboard. There's nothing magical about spruce.

[Bob Hammond]

That's true, in terms of any particular softwood's physical properties. Aside from the need to provide a support for a bridge and to protect the styrofoam, the spruce also provides a 'visual-psycho' (artistic) property that is important to many persons. That's part of the styrofoam cello's style.

Hmm, I wonder if the spruce is bridging across two pieces of styrofoam, or if it's just glued down to a continuous sheet?

[Aaron Helt]

Interesting. Thanks.

[Randolph Rhett]

I found an alternative for my arch tops

[Dennis Duross]

Alan:

Are you saying that softwoods with the same density (weight?) have the same strength?

And the same qualities as tone wood?

[Stephen Neal Saqui]

I wonder if a plucked instrument like a guitar would behave differently than the cello. My guess is that the plucked note would be absorbed, having much less sustain. The cello, being bowed, has a "driven" note and doesn't rely on sustain like a guitar does.

[Alan Carruth]

Softwoods with the same density tend to have the same Young's modulus (E) along the grain. In my measurements, about 60% of the samples fall within 10% of the same line if you plot E against density. Young's modulus is a measure of how much work you have to do to to stretch a given size piece by a certain amount. Since most of the resistance to bending comes from the surfaces of the wood stretching and compressing it's a good predictor of stiffness at a given thickness.

This is NOT a measure of strength: the force it would take to rupture the piece. The two more or less go together, but some woods are tougher than others, and will break at a lower force even though they may have the same Young's modulus. This shows up more on cross grain samples: WRC and redwood both can have high E values across the grain, but also be prone to splitting compared with spruce.

Another consideration is surface hardness. Balsa tends to have a high Young's modulus for it's density, but it has a very soft surface that dents easily. The balsa topped fiddles that I've seen have a spruce pad on the surface where the bridge sits, and also probably another on the inside for the sound post. I've got a WRC gutiar top in my stash that has the same properties of density and stiffness as a Red spruce top that I have, but the cedar has a much softer surface.

It's often said that spruce is the best wood for guitar tops because it has the highest stiffness to weight ratio of any wood. This is not really true. Technically, the stiffness to weight ratio is a structural property, not a material one: you can often get a higher stiffness to weight ratio from a balsa top simply by making it thicker. For that matter, it would be possible to make a 'sandwich' top from almost any hardwood veneer and Nomex that would have the same stiffness as a solid spruce top and weigh less. However, when you consider all the properties, such as crushing resistance, breaking strength, and so on, it is hard to beat spruce overall for a solid top. That, ease of use, and availability, are the reasons it's so popular, I think.

[Mark Langner]

Guess I'd better get my sassafras (back and sides) and white pine (top) archtop done. Actually, I have done one archtop with a (mostly) white pine top (spruce strip down the center for artistic effect) and it's a gem.

[Clay Schaeffer]

" However, when you consider all the properties, such as crushing resistance, breaking strength, and so on, it is hard to beat spruce overall for a solid top. That, ease of use, and availability, are the reasons it's so popular, I think."

But all spruce is not created equal. Depending on the way it grows and the way it is cut, it can vary a lot in it's cosmetic and physical properties. "Mastergrade" sets already seem rare and pricey to me.

[Pete Halliday]

Randolph...more information, please!

[Randolph Rhett]

Randolph...more information, please!

I don't want to hijack this thread. I was being facetious. That is my CFA-1, a ridiculous moniker for a guitar I've only made three of. The soundboard is carbon fiber/nomex composite. No spruce.

To my ears, it's the best acoustic sounding archtop I've ever played. Of course, as a proud papa I'm likely somewhat biased I don't have a good acoustic recording of it yet. A friend has a good home studio, but haven't had a chance to go there. I have a small build thread over on OLF, for a little more info.

[Bob Hammond]

There's no hijacking here. The idea was/is to stimulate discussion.

[Alan Carruth]

Clay Schaeffer wrote:
" "Mastergrade" sets already seem rare and pricey to me."

Sure, but master grade wood is not acoustically or structurally better than lower grades, it just looks more like what people have been trained to think of as 'tone wood'. Some of the best sounding tops I've used have been cosmetically pretty bad, and some of the 'master grade' stuff I've paid big bucks for has been just about useless. Of course, those of us who know better have a hard time going up against all the tradition and the current advertising budgets that are convincing people that they MUST pay a lot for an upgrade if they want good sound.

[Clay Schaeffer]

" master grade wood is not acoustically or structurally better than lower grades, it just looks more like what people have been trained to think of as 'tone wood'. Some of the best sounding tops I've used have been cosmetically pretty bad, and some of the 'master grade' stuff I've paid big bucks for has been just about useless. Of course, those of us who know better have a hard time going up against all the tradition and the current advertising budgets that are convincing people that they MUST pay a lot for an upgrade if they want good sound."


Agreed! That's one reason it's as scarce as hen's teeth in my shop!